They want the court, convened once each year to hear public representations, to demand the city council rethinks its support of the scheme.

Hampshire Against Fluoridation (HAF) will say the council’s vote was held before the outcome of the public consultation was known, which showed that 72 per cent of responses were not in favour of proceeding with water fluoridation.

In a separate phone survey of 2,000 residents, 38 per cent of people questioned opposed the scheme, compared to 32 per cent in favour of it. HAF spokesman Steve Peckham said: “The support of the city council was quoted by the strategic health authority as one of the main reasons for them going ahead.

“But when the city council took the decision to support the primary care trust’s request it didn’t know about the level of dissent or the majority people were against it.”

The court meets in public at 11am today in council chamber at the Civic Centre.